Foaming technology in long glass fiber filled materials

ABSTRACT

A foamed part, includes: a long glass fiber filled polymeric material, wherein the long glass fibers have an initial length before molding of the foamed part and a final length after molding of the foamed part; wherein a post-molding length of the long glass fibers in the foamed part is greater than or equal to a post-molding length of long glass fibers in a similarly dimensioned foamed part made without a pressurized plasticizing unit.

BACKGROUND

Certain formed polymeric parts, e.g., automotive parts, are continuallydesired to be lighter in weight without a reduction in mechanical orphysical properties of the part. Foamed injection molding can provide alighter weight part as compared to a part formed by other methods, butusing foamed injection molding with long glass fiber filled materialscan result in fiber breakage with intrinsic loss of mechanicalproperties such as strength, stiffness, and impact resistance.

Thus there is a need in the art for a part made from a long glass fiberfilled material that is lighter in weight without a breakage in the longglass fibers.

BRIEF DESCRIPTION

The above described and other features are exemplified by the followingfigures and detailed description.

A method of making a foamed part, comprises: introducing a long glassfiber filled polymeric material to a hopper of an injection moldingmachine, wherein the long glass fibers have a pre-molding length;melting the long glass fiber filled polymeric material to form a melt;pressurizing a plasticizing unit of the injection molding machine with ablowing agent, wherein a seal is located between a rotating part and afixed part of the plasticizing unit; having a seal between the rotatingand fixed parts of the plasticizing unit; sealing the plasticizing unitwith an airlock mounted between a barrel of the injection moldingmachine and the hopper; increasing a pressure of the blowing agent andincreasing a back pressure of the injection molding machine tohomogenize the melt and the blowing agent; and forming the foamed part;wherein a post-molding length of the long glass fibers in the foamedpart is greater than or equal to a post-molding length of long glassfibers in a similarly dimensioned foamed part made without thepressurized plasticizing unit.

A foamed part, comprises: a long glass fiber filled polymeric material,wherein the long glass fibers have an initial length before molding ofthe foamed part and a final length after molding of the foamed part;wherein a post-molding length of the long glass fibers in the foamedpart is greater than or equal to a post-molding length of long glassfibers in a similarly dimensioned foamed part made without a pressurizedplasticizing unit.

BRIEF DESCRIPTION OF THE DRAWINGS

Refer now to the figures, which are exemplary embodiments, and whereinthe like elements are numbered alike.

FIGS. 1A to 1F are pictures of cut sections of foamed plaques showingthe cell structure and density with a 30% weight reduction.

FIGS. 2A to 2F are pictures of cut sections of foamed plaques showingthe cell structure and density with a 20% weight reduction.

FIG. 3A to 3C are pictures of a foamed plaque illustrating positionswhere cut sections of the cell structure via light microscopy anddensity measurements were taken.

FIGS. 4A and 4B are pictures of a foamed plaque illustrating positionswhere light microscopy was performed on decompression samples.

FIGS. 5A to 5D are pictures of a cut section of the foamed plaque with2.3 times the original thickness molded with Composition No. 2.

FIGS. 6A and 6B are pictures of a cut section of the foamed plaque with4 times the original thickness molded with Composition No. 5.

FIG. 7 is a graphical illustration of fiber length measurements in themolded parts.

FIG. 8 is a graphical illustration of the number of long fibers in themolded parts made by solid injection molding and made by foaminginjection molding.

FIG. 9 is a graphical illustration of the ash content in solid andfoamed parts.

FIG. 10 is a graphical illustration of the flow length versus density ofmolded parts as described herein.

FIG. 11 is a graphical illustration of various molded samples and theircorresponding fiber length.

FIGS. 12A-12D are graphical illustrations of the flexural strength ofvarious molded samples as described herein.

FIGS. 13A and 13B are graphical illustrations of the impact strength ofvarious molded samples as described herein.

FIGS. 14A and 14B are graphical illustrations of the impact strength ofdisplacement molded samples as described herein.

DETAILED DESCRIPTION

Disclosed herein are foamed parts and methods of making foamed parts.The foamed part can be made from a long glass fiber filled polymericmaterial. The long glass fibers can have an initial length beforemolding of the foamed part and a final length after molding of thefoamed part. The final length of the long glass fibers in the foamedpart is greater than or equal to a final length of long glass fibers ina non-foamed part. Without breakage of the long glass fibers in thefoamed part, certain mechanical properties such as strength, stiffness,and impact resistance can be comparable to non-foamed (e.g., solid)parts, with a reduction in weight as compared to solid parts. Thetechnology used to manufacture parts from long glass fiber filledmaterials such that an average fiber length in the final part can bereduced by less than a reduction in an average fiber length in the finalpart made by other foaming technologies, e.g., using a chemical blowingagent or physical foaming agent, can include placing an injection screwunder pressure with a relatively flat pressure profile. Such amanufacturing process can help ensure the long glass fibers do not breakduring the forming process.

Foaming technologies, such as the use of a chemical blowing agent orphysical foaming agent, can lead to excessive fiber breakage, whichdirectly affects the mechanical and physical properties of a part madewith these methods using a long glass fiber filled material.Consequently, performance enhancements observed by using long glassfiber filled materials, instead of short glass fiber filled materialscan be erased. Long glass fiber breakage can occur due to shear stressapplied during the homogenization phase of the process where the gas,(whether coming from a chemical or physical blowing agent), ishomogenized with the molten polymeric material. If the glass fiberlength can be held constant, or even increased, as compared to otherprocesses, during the injection foaming process, the reduction ofproperties, including impact resistance, due to foaming, can beminimized and even further weight reduction in the resulting part can beachieved.

The use of foaming agents in polymeric materials can reduce density andthus, also reduce weight of a final part. The addition of the foamingagents, whether chemical or physical, leads to the formation of acellular structure inside the molded part through the dispersion of gasbubbles inside the basic polymeric material. Foam molding can offer thepossibility of increasing the size of a part without increasing theweight and reducing the weight of a part with a controlled change inproperties. Other valuable advantages for foaming are cycle timereduction, improved dimensional uniformity, and increased cavitation ina mold.

In chemical foaming, the gas is generated by chemical decomposition of ablowing agent. The blowing agent is added as a masterbatch system. Thedecomposition is initiated by heat of the melt during plasticizing.Endothermic foaming agents are mainly used for injection molding. Theyare based on bicarbonate and citric acid substances. Chemical foaminginvolves mixing a chemical blowing agent with pellets prior to thepellets being fed into the feed throat of an injection molding machine.The blowing agent decomposes while the resin is melting, releasing a gassuch as nitrogen that is mixed with the polymer. Endothermic foamingagents can be used for injection molding. The endothermic foaming agentscan be based upon bicarbonate and citric acid substances. As the polymeris injected into the mold, the gas expands. The bubbles formed help packthe resin in the mold. Chemical foaming can be done on any existingmolding machine with the only restriction that a blowing agent be usedthat decomposes at a temperature compatible with the processingtemperature of the polymer. Using chemical foaming with long glass fiberfilled polymeric materials can result in a reduction in the long glassfibers of about 20% as compared to solid injection molding (i.e.,non-foamed injection molding), due to an increase in back pressureapplied for homogenization of the melt during the plastification stageof the process. To compensate for the loss in mechanical properties dueto the decrease in the length of the long glass fibers, decompressiontechnology can be applied. Decompression refers to increasing the partthickness by opening the mold immediately after filling the cavity.

Foaming can be started using standard injection molding conditions forthe resin being molded. To adjust the level of foaming, pack pressureand/or packing time should be changed. A decrease in packing willincrease foaming and an increase in packing will decrease foaming.Setting the stroke to produce a short shot will also increase the amountof foaming. It can also be desirable to adjust the level of foamingagent used, the melt temperature being used, or the type of foamingagent used. Faster cycle times can be achieved by reducing the packingtime. This is possible since the gas pressure in the part is actuallypacking the part and not hydraulic pressure.

Physical foaming can be achieved by adding a gas such as nitrogen,oxygen, or carbon dioxide within a defined pressure and temperaturerange to the polymer melt and generally requires a special screw designwith mixing elements located in front of the screw. Within this rangethe gas becomes a supercritical fluid and can be dissolved within thepolymer melt during plasticizing. Various techniques can be used to addthe gas to the melt as a supercritical fluid, including adding the gasto the melt in the machine barrel (technique 1) and adding the gas tothe melt in an adapted hot runner system (technique 2).

Technique 1 involves metering a gas such as nitrogen into the polymermelt stream as it moves down the barrel. The gas is thoroughly mixedinto the polymer creating a single phase solution of polymer and gas.Nucleation from the pressure drop of the resin being injected into themold causes gas bubble formation and cell growth occurs while the partcools, packing the resin into the mold like chemical foaming. Topractice foaming using technique 1, special gas delivery equipment needsto be purchased and the injection molding machine needs to be modified.As mentioned, mixing elements are located in front of the screw. Thesemixing elements cause severe glass fiber breakage.

The level of foaming can be adjusted much like it is in chemical foamingby altering the injection molding process. However, the level of gas inthe resin is more controlled in technique 1 and is not limited byfinding a blowing agent that decomposes at the right temperature for agiven process. The process is limited by the short distance within thebarrel where the gas is introduced and has to be homogenized with themelt. By consequence the amount of shear applied over this distance ishigh. A type of mixing element is used which can apply a high shear loadto the melt, thereby causing glass fiber breakage. For example, theaverage fiber length can be reduced by 25%, for example, 30%, forexample, 40% as compared to similarly dimensioned solid parts.

In any foaming process the surface of the part will show a lot of splaydue to gas in the resin being smeared between the resin and the surfaceof the mold. The amount of splay will depend on the level of gas and thelevel of weight reduction and to some degree the resin being foamed.

In the process disclosed herein to make a part using a long glass fiberfilled polymeric material, without a reduction in fiber length, theplasticizing unit of the injection molding machine can be pressurizedwith a gaseous blowing agent. To prevent the loss of blowing agent atthe end of the screw, a seal can be installed between the screw shaftand the plasticizing cylinder. The plasticizing unit can be sealed withan airlock that is mounted between the barrel and the material hopper.Similar to other foaming processes, the plasticizing unit can beequipped with a shut-off nozzle and a position control for the screw tokeep the blowing-agent-loaded melt under pressure until it is injectedinto the mold.

With the use of such a processing technique, the fiber length of thelong glass fibers in the foamed part after molding can be greater thanor equal to the fiber length of long glass fibers in solid molding. Forexample, the fiber length can be increased 5% to 40% as compared to anon-foamed part. The fiber length can be increased greater than or equalto 5%. The fiber length can be increased greater than or equal to 10%.The fiber length can be increased greater than or equal to 20%. Thefiber length can be increased greater than or equal to 25%. The fiberlength can be increased greater than or equal to 30%. The fiber lengthcan be increased greater than or equal to 40%.

Desirable processing conditions can be achieved when an increase in gaspressure is accompanied by an increase of the back pressure, with adifference between the two of greater than or equal to −1 to 10megaPascals (MPa). The difference can be 0 to 7 MPa. The difference canbe 0 to 5 MPa. The difference can be 0 to 0.5 MPa. The difference can be0.1 to 0.4 MPa. The blowing agent pressure can be 0.1 to 10 MPa, forexample, 0.5 to 7.5 MPa, for example 0.75 to 6 MPa, for example 1.5 to 5MPa, for example, 2.0 to 4.0 MPa. The injection pressure of theinjection molding machine can be reduced by greater than or equal to 10%less in making the foamed part including long glass fibers as comparedto the injection pressured used to make a similarly dimensionednon-foamed part including long glass fibers. For example, the injectionpressure can be reduced by greater than or equal to 20%, for example,greater than or equal to 30% less, for example, greater than or equal to40% less. A difference between back pressure and the blowing agentpressure of the injection molding machine can be 0 to 10 MPa, forexample, 0 to 5 MPa, for example, 0 to 2.5 MPa.

With this setup, the plasticizing unit can be pressurized with anyblowing agent that is gaseous at room temperature up to the pressurewhere the blowing agent liquefies. The equipment can be used withblowing agent pressures of greater than or equal to 7.5 MPa, forexample, greater than or equal to 10 MPa, for example, greater than orequal to 15 MPa, for example, greater than or equal to 20 MPa.

The gaseous blowing agent diffuses into the polymer pellets in theplasticizing unit. The time required for saturation of the polymerdecreases by increasing the temperature due to the higher diffusion rateat higher temperatures. Therefore, the diffusion in the plasticizingunit is fast enough to allow a continuous injection molding productionwith cycle times of less than or equal to 40 seconds for preloading thepolymer with gas. The cycle time can be less than or equal to 35seconds. The cycle time can be less than or equal to 30 seconds. Thecycle time can be less than or equal to 25 seconds. The blowing agent isdissolved in the molten polymer. As a result, no additional mixingelements which might damage the polymeric material or the glass fibersdue to additional shear are necessary.

Blowing agents for this process can include carbon dioxide and nitrogenat pressures of 0.5 to 5.0 MPa, for example greater than or equal to 5.0MPa. Since the foaming process can be controlled by only two additionalprocess parameters, i.e., type of blowing agent and pressure, themethods disclosed herein for forming a foamed polymer part using longglass fiber filled polymeric material can be accomplished as easily aswith chemical blowing agents.

Possible polymeric resins that may be employed include, but are notlimited to, oligomers, polymers, ionomers, dendrimers, copolymers suchas graft copolymers, block copolymers (e.g., star block copolymers,random copolymers, etc.) and combinations comprising at least one of theforegoing. Examples of such polymeric resins include, but are notlimited to, polycarbonates (e.g., blends of polycarbonate (such as,polycarbonate-polybutadiene blends, copolyester polycarbonates)),polystyrenes (e.g., copolymers of polycarbonate and styrene,polyphenylene ether-polystyrene blends), polyimides (e.g.,polyetherimides), acrylonitrile-styrene-butadiene (ABS),polyalkylmethacrylates (e.g., polymethylmethacrylates), polyesters(e.g., copolyesters, polythioesters), polyolefins (e.g., polypropylenesand polyethylenes, high density polyethylenes, low densitypolyethylenes, linear low density polyethylenes), polyamides (e.g.,polyamideimides), polyarylates, polysulfones (e.g., polyarylsulfones,polysulfonamides), polyphenylene sulfides, polytetrafluoroethylenes,polyethers (e.g., polyether ketones, polyether etherketones,polyethersulfones), polyacrylics, polyacetals, polybenzoxazoles (e.g.,polybenzothiazinophenothiazines, polybenzothiazoles), polyoxadiazoles,polypyrazinoquinoxalines, polypyromellitimides, polyquinoxalines,polybenzimidazoles, polyoxindoles, polyoxoisoindolines (e.g.,polydioxoisoindolines), polytriazines, polypyridazines, polypiperazines,polypyridines, polypiperidines, polytriazoles, polypyrazoles,polypyrrolidines, polycarboranes, polyoxabicyclononanes,polydibenzofurans, polyphthalides, polyacetals, polyanhydrides,polyvinyls (e.g., polyvinyl ethers, polyvinyl thioethers, polyvinylalcohols, polyvinyl ketones, polyvinyl halides, polyvinyl nitriles,polyvinyl esters, polyvinylchlorides), polysulfonates, polysulfides,polyureas, polyphosphazenes, polysilazzanes, polysiloxanes, andcombinations comprising at least one of the foregoing.

More particularly, the polymeric can include, but is not limited to,polycarbonate resins (e.g., LEXAN™ resins, commercially available fromSABIC's Innovative Plastics business such as LEXAN™ XHT, LEXAN™ HFD,etc.), polyphenylene ether-polystyrene blends (e.g., NORYL™ resins,commercially available from SABIC's Innovative Plastics business),polyetherimide resins (e.g., ULTEM™ resins, commercially available fromSABIC's Innovative Plastics business), polybutyleneterephthalate-polycarbonate blends (e.g., XENOY™ resins, commerciallyavailable from SABIC's Innovative Plastics business),copolyestercarbonate resins (e.g. LEXAN™ SLX or LEXAN™ FST resins,commercially available from SABIC's Innovative Plastics business),acrylonitrile butadiene styrene resins (e.g., CYCOLOY™ resins,commercially available from SABIC's Innovative Plastics business),polyetherimide/siloxane resins (e.g., SILTEM™, commercially availablefrom SABIC's Innovative Plastics business), polypropylene resins, forexample, long glass fiber filled polypropylene resins (e.g., STAMAX™resins, commercially available from SABIC's Innovative Plasticsbusiness), and combinations comprising at least one of the foregoingresins. Even more particularly, the polymeric resins can include, butare not limited to, homopolymers and copolymers of a polycarbonate, apolyester, a polyacrylate, a polyamide, a polyetherimide, apolyphenylene ether, or a combination comprising at least one of theforegoing resins. The polycarbonate can comprise copolymers ofpolycarbonate (e.g., polycarbonate-polysiloxane, such aspolycarbonate-polysiloxane block copolymer), linear polycarbonate,branched polycarbonate, end-capped polycarbonate (e.g., nitrileend-capped polycarbonate) blends of PC, such as PC/ABS blend, andcombinations comprising at least one of the foregoing, for example acombination of branched and linear polycarbonate.

In order to attain the desired lightweight foamed part, the polymericmaterial can also comprise blowing agent(s). The blowing agent(s) can beof the decomposition type (evolves a gas (e.g., carbon dioxide (CO₂),nitrogen (N₂), and/or ammonia gas) upon chemical decomposition), and/oran evaporation type (which vaporizes without chemical reaction).Possible blowing agents include, carbon dioxide, sodium bicarbonate,azide compounds, ammonium carbonate, ammonium nitrite, monosodiumcitrate, light metals which evolve hydrogen upon reaction with water,chlorinated hydrocarbons, chlorofluorocarbons, azodicarbonamide,N,N′dinitrosopentamethylenetetramine, trichloromonofluoromethane,trichlorotrifluoroethane, methylene chloride, organic carboxylic acids(such as formic acid, acetic acid, oxalic acid, ricinoleic acid, and soforth), pentane, butane, ethanol, acetone, nitrogen gas (N₂), ammoniagas, and so forth, as well as combinations comprising at least one ofthe foregoing. Exemplary commercial blowing agents useful for extrusionand molding include, but are not limited to, 6257 ID Endo Foam 35 XFC,5767 ID Endo Foam 100FC, 8812 ID Exo Foam 80, 8861 ID 25, 6851 ID 35MFC, 6400 ID 35 NA, 6295 ID 70 XFC, 6265 ID 70 MFC, 7800 ID 70 NA, 6905ID 90 NA, 6906 ID 90 NA FC, 6258 ID 100 XFC 100, 6836 ID 130 MFC, 6950ID 40 EEFC, 6952 ID 40 EEXFC, 6112 ID 70 EEFC, 6833 ID 70 EEFC, 8085 ID70 EEMFC, 7236 ID Foam EEFC, 7284 ID 80 2300 EXO, 7285 OD 80 2400 EXO,71531 ID 100 MFC EXO, 8016 ID 120 EXO, 6831 ID 135 EXO, Palmarole EXP141/92B, Palmarole BA.K2.S1, Palmarole BA.F4.S, Palmarole BA.F2.S,Palmarole BA.K5.S, Palmarole BA.F4.E.MG, Palmarole BA.K3.EF, PalmaroleBA.M4.E, Palmarole MB.BA10, Palmarole MB.BA.13, Palmarole MB.BA.15,Palmarole MB.BA.16, Palmarole MB.BA.18, Palmarole BA.M7.E, PalmaroleBA.K2.S1, Palmarole BA.F4.S, Palmarole BA.K4.S, Palmarole BA.F2.S,Palmarole BA.K3.EF, Palmarole BA.K4.C, and Bergen InternationalFoamazol™ series 32, 40, 41, 43, 50, 57, 60, 61, 62, 63, 70, 71, 72, 73,73S, 90, 91, 92, 93, 94, 95, 96, as well as X0-255, X0-256, X0286,X0-330, X0-339, X0-355, X0-379, X0-385, X0-423, X0P-300, X0P-301,X0P-305, and X0P-341.

The blowing agent can be at least one from carbon dioxide, sodiumbicarbonate, azide compounds, ammonium carbonate, ammonium nitrite,monosodium citrate, light metals which evolve hydrogen upon reactionwith water, chlorinated hydrocarbons, chlorofluorocarbons,azodicarbonamide, N,N′dinitrosopentamethylenetetramine,trichloromonofluoromethane, trichlorotrifluoroethane, methylenechloride, organic carboxylic acids (such as formic acid, acetic acid,oxalic acid, ricinoleic acid, and so forth), pentane, butane, ethanol,acetone, oxygen gas, nitrogen gas, ammonia gas, and combinationscomprising at least one of the foregoing.

When using some classes of blowing agents, endothermic or exothermictypes or combinations thereof, CO₂ gas is released and eventually exitsthe extruder as bubbles dispersed in the polymer melt. The bubblesexpand to form cells which make up the lightweight foamed part. Thecells can be open or closed, but generally are closed. The cells canhave an aspect ratio of less than or equal to 10, specifically, lessthan or equal to 7.5, more specifically, less than or equal to 5, evenmore specifically, less than or equal to 3. The cells can have a size ofless than or equal to 5 millimeters (mm), for example, less than orequal to 2.5 mm, for example, less than or equal to 1 mm, for example,less than or equal to 500 micrometers (μm). The cell size can be lessthan or equal to 250 micrometers, for example, less than or equal to 200micrometers, for example, less than or equal to 100 micrometers, forexample, less than or equal to 50 micrometers, and for example, lessthan or equal to 20 micrometers. The amount of chemical blowing agentemployed is dependent upon the process, processing conditions, and thespecific polymeric material(s).

In some embodiments, the amount of blowing agent can be 0.1 wt. % to 10wt. %, or, for example, 0.1 wt. % to 5 wt. %, or, for example, 1 wt. %to 4 wt. %, wherein the weight percent is based upon a total weight ofthe polymer composition (e.g., polymeric material(s), additive(s),blowing agent(s), nucleating agent(s), etc.) In some embodiments, theblowing agent can be 0.1 wt. % to 4 wt. %, or, for example, 0.5 wt. % to3 wt. %, and 0.25 wt. % to 2 wt. % of an additional, different blowingagent(s), or, for example, 0.5 wt. % to 1.5 wt. % of the additionalblowing agent(s). These physical blowing agents encompass CO₂, N₂, H₂O,O₂, acetone, butane, and argon. Ozone depleting agents can be avoideddue to environmental concerns.

It is anticipated that the choice of resin additive package will bebased upon the blowing agent. In other words, an additive package willbe included so as to counteract any counterion produced by the blowingagent. Therefore, an additive can be included in the composition suchthat the pH can be maintained in a desired range such that whencounterions are produced they are neutralized. The desired pH will bedependent upon the particular polymeric material. A buffer can be addedto the composition (polymer material) to neutralize counterions producedby the blowing agent. The lightweight sheet performance for long-termphysical and mechanical properties including low-and-high temperaturecycling performance, elevated temperature performance, resistance toenvironmental effects such as high humidity, etc., is influenced byresin stability. The resin additive package would be required to providehydrolytic stability for performance of the chemical and/or physicalblowing agent, by-products, and nucleation sites in the same manner asit would prevent premature resin decomposition during, for instance, anaggressive extrusion processing step.

During the manufacturing of the lightweight foamed part, most chemicalblowing agents leave the residues of the decomposition products in thepolymer matrix that may be harmful to the polymer, e.g., that candeteriorate chemical resistance or hydrothermal resistance of thepolymer matrix. Choice of chemical blowing agent is important forpoly-condensation type polymers such as polycarbonates, polyarylates,polyesters and polyetherimides to minimize the harm. For example, ifsodium bicarbonate is used as chemical blowing agent for makinglight-weight polycarbonate sheets, sodium bicarbonate thermallydecomposes during the polycarbonate melt processing step into sodiumcarbonate, water and carbon dioxide, of which water and carbon dioxidework as blowing agent gas to form foamed structure in the polycarbonatesheet while the sodium carbonate residue left inside the finalpolycarbonate foamed sheet is a relatively strong base that can harmhydrothermal resistance of the polycarbonate matrix if the hydrothermalresistance properties or long-term physical and mechanical propertiesretention is desired. On the other side, some other chemical blowingagents, with neutral or weak acid or weak base nature of theirdecomposition product residue at the temperature of the foaming process,may be friendlier to polycarbonate. The examples include mono-sodiumcitrate, citric acid, 5-phenyl-3,6-dihydro-2H-1,3,4-oxadiazin-2-one(PEDOX), 5-phenyl-1H-Tetrazole (5-PT), as well as combinationscomprising at least one of these chemical blowing agents.

The polymeric material includes long glass fibers. Long glass fibers asdescribed herein, include glass fibers with an initial length of greaterthan or equal to 3 mm. The polymeric can include various additivesordinarily incorporated into polymer compositions of this type, with theproviso that the additive(s) are selected so as to not significantlyadversely affect the desired properties of the foamed part, inparticular, mechanical properties, such as impact resistance. Suchadditives can be mixed at a suitable time during the mixing of thepolymeric material for the foamed part. Exemplary additives includeimpact modifiers, fillers, reinforcing agents, antioxidants, heatstabilizers, light stabilizers, ultraviolet (UV) light stabilizers,plasticizers, lubricants, mold release agents, antistatic agents,colorants (such as carbon black and organic dyes), surface effectadditives, anti-ozonants, thermal stabilizers, anti-corrosion additives,flow promoters, pigments, dyes radiation stabilizers (e.g., infraredabsorbing), flame retardants, and anti-drip agents. A combination ofadditives can be used, for example a combination of a heat stabilizer,mold release agent, and ultraviolet light stabilizer. In general, theadditives are used in the amounts generally known to be effective. Thetotal amount of additives (other than any impact modifier, filler, orreinforcing agent) is generally 0.001 wt % to 5 wt %, based on the totalweight of the polymeric material composition.

A method of making a foamed part can include introducing a long glassfiber filled polymeric material to a hopper of an injection moldingmachine, where the long glass fibers can have an initial, pre-moldinglength. The long glass fiber filled polymeric material can then bemelted. A plasticizing unit of an injection molding machine can then bepressurized with a blowing agent, where a seal can be located between arotating part and a fixed part of the plasticizing unit. Theplasticizing unit can then be sealed with an airlock mounted between abarrel of the injection molding machine to homogenize the melt and theblowing agent. The foamed part can then be formed. In a foamed part madeby this process, a post-molding length of the long glass fibers in thefoamed part can be greater than or equal to a post-molding length oflong glass fibers in a similarly dimensioned foamed part made byinjection molding without the pressurized plasticizing unit. Thepost-molding length of the long glass fibers can be greater than orequal to a post-molding length of long glass fibers in a similarlydimensioned solid (i.e., non-foamed) part.

A weight of the foamed part can be reduced by greater than or equal to5% as compared to a similarly dimensioned non-foamed part including longglass fibers. For example, the weight reduction can be greater than orequal to 10%. The weight reduction can be greater than or equal to 20%.The weight reduction can be greater than or equal to 30%. Thicknessshrinkage of the foamed part can also be reduced when processed via themethod disclosed herein with the pressurized unit on the injectionmolding machine. For example, for a foamed injected plaque with anominal thickness e.g., 3 mm, a foamed part can have almost 50% lessthickness shrinkage than a solid part. For example, for a foamedinjected plaque with a nominal thickness of 3 mm, a foamed part can havea thickness of 2.92 mm, while a solid part can have a thickness of 2.85mm. The foamed part in this instance has nearly 50% less thicknessshrinkage than the solid part. For example, a foamed injected plaquewith a nominal thickness made using the process disclosed herein canhave 5% less thickness shrinkage, for example 10% less thicknessshrinkage, for example 25% less thickness shrinkage, for example 30%less thickness shrinkage, for example, 50% less thickness shrinkage, forexample, 65% less thickness shrinkage as compared to a non-foamedinjected plaque.

Formed articles include, for example, computer and business machinehousings, home appliances, trays, plates, handles, helmets, automotiveparts such as instrument panels, cup holders, glove boxes, interiorcoverings and the like. In various further aspects, formed articlesinclude, but are not limited to, food service items, medical devices,animal cages, electrical connectors, enclosures for electricalequipment, electric motor parts, power distribution equipment,communication equipment, computers and the like, including devices thathave molded in snap fit connectors. In a further aspect, articles of thepresent invention comprise exterior body panels and parts for outdoorvehicles and devices including automobiles, protected graphics such assigns, outdoor enclosures such as telecommunication and electricalconnection boxes, and construction applications such as roof sections,wall panels and glazing. Multilayer articles made of the disclosedpolycarbonates particularly include articles which will be exposed toUV-light, whether natural or artificial, during their lifetimes, andmost particularly outdoor articles; i.e., those intended for outdooruse. Suitable articles are exemplified by enclosures, housings, panels,and parts for outdoor vehicles and devices; enclosures for electricaland telecommunication devices; outdoor furniture; aircraft components;boats and marine equipment, including trim, enclosures, and housings;outboard motor housings; depth finder housings, personal water-craft;jet-skis; pools; spas; hot-tubs; steps; step coverings; building andconstruction applications such as glazing, roofs, windows, floors,decorative window furnishings or treatments; treated glass covers forpictures, paintings, posters, and like display items; wall panels, anddoors; protected graphics; outdoor and indoor signs; enclosures,housings, panels, and parts for automatic teller machines (ATM);enclosures, housings, panels, and parts for lawn and garden tractors,lawn mowers, and tools, including lawn and garden tools; window and doortrim; sports equipment and toys; enclosures, housings, panels, and partsfor snowmobiles; recreational vehicle panels and components; playgroundequipment; articles made from plastic-wood combinations; golf coursemarkers; utility pit covers; computer housings; desk-top computerhousings; portable computer housings; lap-top computer housings;palm-held computer housings; monitor housings; printer housings;keyboards; facsimile machine housings; copier housings; telephonehousings; mobile phone housings; radio sender housings; radio receiverhousings; light fixtures; lighting appliances; network interface devicehousings; transformer housings; air conditioner housings; cladding orseating for public transportation; cladding or seating for trains,subways, or buses; meter housings; antenna housings; cladding forsatellite dishes; coated helmets and personal protective equipment;coated synthetic or natural textiles; coated photographic film andphotographic prints; coated painted articles; coated dyed articles;coated fluorescent articles; coated foam articles; and likeapplications.

In one aspect, the foamed parts can include articles comprising thedisclosed long glass fiber filled polymeric materials. In a furtheraspect, the article comprising the disclosed long glass fiber filledpolymeric materials can be used in automotive applications. In a yetfurther aspect, the article comprising the disclosed long glass fiberfilled polymeric materials can be selected from instrument panels,overhead consoles, interior trim, center consoles, panels, quarterpanels, rocker panels, trim, fenders, doors, deck lids, trunk lids,hoods, bonnets, roofs, bumpers, fascia, grilles, minor housings, pillarappliqus, cladding, body side moldings, wheel covers, hubcaps, doorhandles, spoilers, window frames, headlamp bezels, headlamps, taillamps, tail lamp housings, tail lamp bezels, license plate enclosures,roof racks, and running boards. In an even further aspect, the articlecomprising the disclosed long glass fiber filled polymeric materials canbe selected from mobile device exteriors, mobile device covers,enclosures for electrical and electronic assemblies, protectiveheadgear, buffer edging for furniture and joinery panels, luggage andprotective carrying cases, small kitchen appliances, and toys.

In one aspect, the foamed parts can include electrical or electronicdevices including the disclosed long glass fiber filled polymericmaterials. In a further aspect, the electrical or electronic device canbe a cellphone, a MP3 player, a computer, a laptop, a camera, a videorecorder, an electronic tablet, a pager, a hand receiver, a video game,a calculator, a wireless car entry device, an automotive part, a filterhousing, a luggage cart, an office chair, a kitchen appliance, anelectrical housing, an electrical connector, a lighting fixture, a lightemitting diode, an electrical part, or a telecommunications part.

The methods disclosed herein can provide favorable results with respectto the use of long glass fiber filled materials since the loss ofmechanical properties due to foaming is less compared with other foamingtechnologies (such as chemical and those foamed with MuCell™ technology)and fiber length is upheld or increased as compared to the originalfiber length in solid moldings. Furthermore, initial cost for adaptingthe injection unit is low as only the pressurizing unit is an additionalcomponent. Weight reduction of the foamed parts can be less than orequal to 65%, for example, less than or equal to 50%, for example, lessthan or equal to 30%, for example, less than or equal to 25%, forexample, less than or equal to 20%, for example, less than or equal to15%, for example, less than or equal to 10%, for example, less than orequal to 5% as compared to a solid (i.e., non-foamed part) part with thesame thickness. In certain applications, a weight reduction of less thanor equal to 20% can also provide the desired impact properties.

EXAMPLES

Various long glass fiber filled polymeric materials were tested usingthe method described herein and compared to a solid material. Table 1list the materials used in the examples. For all tests, 140 mm×90 mm×3mm plaque was molded with a 1.2 mm film gate, and a 35 mm injectionmolding machine barrel. The injection molding machine used forprocessing of the long glass fiber filled polymeric materials was anArburg Allrounder 520 A 1500-400. Another tool with a central gatediameter equal to 2.5 mm was used for decompression molding (opening ofthe tool after filling). The mold had dimensions of 200 mm×100 mm andvariable thickness. Compositions 1 to 5 included a long glass fiberfilled polypropylene polymeric material commercially available fromSABIC's Innovative Plastics business. Composition 6 included a shortglass fiber filled polypropylene compound (PPC) commercially availablefrom SABIC's Innovative Plastics business. Microanalysis was used toevaluate gas distribution within the foamed samples. Samples were cut tosize with the use of a band saw. For cross-sectional images, sampleswere embedded in epoxy resin. All samples were polished with a polishingmachine and images were done with light microscopy. For densitymeasurements, dimensions were measured with a caliper an weighed on ananalytical balance. “YM” in the material description refers to apolypropylene monomer, while “YK” in the material description refers toa polypropylene copolymer.

TABLE 1 Materials Information Composition No. Grade % Fiber ContentCompany 1 STAMAX ™ 20% long glass fiber SABIC's Innovative 20YM240Plastics Business 2 STAMAX ™ 30% long glass fiber SABIC's Innovative30YM240 Plastics Business 3 STAMAX ™ 40% long glass fiber SABIC'sInnovative 40YM240 Plastics Business 4 STAMAX ™ 20% long glass fiberSABIC's Innovative 20YK270E Plastics Business 5 STAMAX ™ 30% long glassfiber SABIC's Innovative 30YK270E Plastics Business

Example 1 Weight Reduction

Weight reduction of the foamed parts, Example Nos. 1-4, and 1-5, havinga thickness of 3 mm as compared to reference parts, Example Nos. 1-1,1-2, and 1-3, having the same thickness, was nearly 30% for alldifferent grades of STAMAX™ used as can be seen in Table 2. Using theprocess disclosed herein, weight reduction can be achieved without anyadditional processing requirements, such as injection decompression.

TABLE 2 Weight Reduction Results Foamed Example Composition SolidInjection Injection Weight Reduction No. No. Weight Weight in % 1-1 143.6 1-2 2 47.2 1-3 3 52 1-4 1 30.5 30 1-5 2 34.6 27

Example 2 Cell Structure and Density

FIGS. 1A to 1F illustrate cut sections of a foamed plaque of Example 1-4having a 30% weight reduction as compared to the same size solid part,Example 1-1. The foamed cells in the final part were well distributed ascan be seen in FIG. 1. Cross and in-flow sections for Example 1-5 showeda weight reduction of greater than 20%. As can be seen in FIGS. 2A to2F, the surface layer was well defined closer to the gate, but thickerto the end. The cell structure appears to be similar in all sections.FIGS. 2A to 2F illustrate cut sections of a foamed plaque of Example 1-5having a 20% weight reduction as compared to the same size solid part,Example 1-2.

As can be seen in Table 3, density measurements performed on sampleswith 20% weight reduction, showed that variation of the density withinthe sample is very low and is almost equal through the differentsections of the part. FIGS. 3A to 3C illustrate the positions on thesamples where the measurements (including samples for microscopyanalysis) were taken, where the gate is indicated by reference number10and the direction of flow is indicated by arrow 12.

TABLE 3 Density through different sections of the plaques Com- AverageDimensions Exam- po- Po- (mm) Vol- Den- ple sition si- thick- ume Weightsity No. No. tion length width ness (cm³) (g) (g/cm³) 2-1 4 G 37.7 20.03.0 2.2 1.916 0.86 2-1 4 H 38.0 20.6 3.0 2.3 2.002 0.87 2-1 4 I 38.620.6 3.0 2.3 2.035 0.87 2-2 5 G 38.9 20.2 3.0 2.3 2.064 0.88 2-2 5 H38.7 20.1 3.0 2.3 2.048 0.88 2-2 5 I 38.5 20.3 3.0 2.3 2.039 0.87 2-3 2G 38.2 20.5 3.0 2.3 1.920 0.82 2-3 2 H 38.4 20.6 3.0 2.4 1.952 0.83 2-32 I 38.6 19.9 3.0 2.3 1.916 0.84

Cross and in-flow sections for plaques molded with STAMAX™ 30YM240, anddecompression to 2.3 times original thickness, i.e., Example 2-3, aredisplayed in FIGS. 4A, 4B, and FIGS. 5A to 5D, where FIGS. 4A and 4Billustrate the positions where the measurements were taken. As can beseen in FIGS. 5A to 5D, the cell structure is much more irregular withsome large gap openings due to decompression (i.e., opening of thetool). Nevertheless the entire structure seems still relatively stableand if eventual improvement of the melt strength of the polymer can beachieved, it is believed that the structure could be quite uniform.

Cross and in-flow sections for plaques molded with STAMAX™ 30YK270E,i.e., Example 2-2 and decompression to 4 times original thickness aredisplayed in FIGS. 6A and 6B. As can be seen, cell structure is notconsistent and clear separation of the layers is observed in the middleof the sample. Although not wishing to be bound by theory, it appears asthough the polymer bonds are not present in the middle of the part andonly the glass fibers establishing connection between the two separatedlayers. This indicates that increase of the thickness by decompressiongreater than 2 to 2.5 times the original thickness is not applicable forapplications with high mechanical requirements, but could be a usefultechnology for applications with sound and insulation requirements.

Core-shell structure is observed in most samples. The core containspolymer resin, glass fibers and voids. The shell contains only polymerresin and glass fibers. The shell thickness can vary from 0.2 mm to 0.5mm, for this particular thickness. The shell becomes thicker whenfurther away from the gate.

Example 3 Processing

In this example, it was found that addition of a foaming agent reducedshrinkage of the injected plaques. The thickness measurement indicatedthat plaques without foaming had a thickness of 2.85 mm and those, whichwere foamed had a measured thickness of 2.92 mm to 2.96 mm.

It was also found that injection pressure could be reduced by 10 to 20%.It was further discovered that the gas pressure has an influence on thefoaming of the part. For example, increase of gas pressure has to beaccompanied by the increase of the back pressure as well, because thegas pressure acts like a contra pressure against back pressure and ifback pressure is under the pressure of the gas, then plasticizing isdifficult. In these examples, a gap of 0.5 MPa was left between the gaspressure and the back pressure. With the use of higher gas pressure andback pressure respectively as well, the weight reduction in the part wasbetter. It was observed that change of the gas pressure from 3.5 MPa to5.0 MPa yields an additional 2.5% weight reduction. However, a negativeimpact on the fiber length was observed.

Use of the higher injection speed led to an additional 1% weightreduction, but also displayed a 10% reduction of the fiber length.Reduction in mechanical properties also has to be considered. Weightreduction with this parameter compared with loss of properties due to afiber breakage is not desirable.

In terms of decompression molding, the packing time, i.e., the timeafter injection when opening of the mold is occurring, has an importantrole in determining the thickness of the surface layer of the moldedpart and also the overall mechanical performance. This time cannot betoo long, because the inner layer still has to be melted, when openingoccurs to allow the gas to expand. Thickness of the part is a mainfactor in determining this time. For the particular parts used in thisstudy, the time was 5 seconds.

Example 4 Fiber Length

Fiber length is a parameter of interest in the mechanical performance oflong glass fiber filled materials. Measurement of the fiber length wasperformed on the purge for all foamed conditions and for conditionswithout foaming as a reference point. Apart from the purge, for allsamples, measurement was done at the end of the flow path at 20 mm ofthe far end of the plaque and for most of the samples fiber measurementwas done also at a position after the gate, i.e., 20 mm after the gate.

Measured fiber length in the specimens collected at 20 mm from the farend of the plaque with solid STAMAX™ material 2 and with foamed STAMAX™material 4 is illustrated in FIG. 7. Examples 4-1 and 4-6 were made fromComposition No. 1 with Example 4-1 being solid and Example 4-6 beingfoamed. Examples 4-2 and 4-7 were made from Composition No. 2 withExample 4-2 being solid and Example 4-7 being foamed. Examples 4-3 and4-8 were made from Composition No. 3 with Example 4-3 being solid andExample 4-8 being foamed. Examples 4-4 and 4-9 were made fromComposition No. 4 with Example 4-4 being solid and Example 4-9 beingfoamed, and Examples 4-5 and 4-10 were made from Composition No. 5 withExample 4-5 being solid and Example 4-10 being foamed. The glass fiberlength in the foamed samples is clearly longer than solid samples. Thisindicates that by applying a pressurized unit during foaming injectionmolding, the glass fiber length is not only maintained as the glassfiber length for solid material, but actually an increase of the fiberlength can be present.

From the results, it is clear that parts processed with foaming havelonger fibers. Table 3 illustrates this advantage. This differencevaries from few percent's up to 30%. Another observation related to afiber length measurements, is the glass content dependency. Withincrease of the glass content into material the length differencedecreases, but for 20% and 30% of the glass content, the lengthdifference is still significant. A conclusion from the fibermeasurements is that with this type of foaming the fiber length did notdecrease, but even better-some increase was observed for foamed samples.This is very beneficial for the LGF materials, since all other foamingtechniques cause certain fiber breakage and reduction of the fiberlength. FIG. 8 illustrates that for Examples 4-1 (solid) and 4-2(foamed), the quantity of long glass fibers, i.e., greater than or equalto 6 mm, are greater in the foamed part.

TABLE 4 Fiber length measurement Measurement* Ex. No. (mm) 4-1 4-6 4-24-7 4-3 4-8 4-4 4-9 4-5 4-10 After Gate 2.1 2.2 1.8 1.8 — — 1.4 1.9 1.41.6 End of Fill 2.0 2.6 1.7 2.0 1.5 1.5 1.3 2.0 1.5 1.6 *Fiber length ismeasured by calcination of the sample and optically measurement of theremaining glass fibers.

FIG. 11 illustrates fiber length measurements in the purge with foamingfor the method disclosed herein and the MuCell™ method. Samples 11-1 and11-2 were made from Composition 1 in Table 1, Samples 11-3 and 11-4 weremade from Composition 2in Table 1, Samples 11-5 and 11-6 were made fromComposition 3 in Table 1, Samples 11-7 and 11-8 were made fromComposition 4 in Table 1, and Samples 11-9 and 11-10 were made fromComposition 5 in Table 1. Samples 11-1, 11-3, 11-5, 11-7, and 11-9 weremade using the method disclosed herein (reference number 14), whileSamples 11-2, 11-4, 11-6, 11-8, and 11-10 were made using the MuCell™method (reference number 16). As can be seen from FIG. 11, fiber lengthin the purge after foaming are greater for each composition tested withthe method disclosed herein.

Example 5 Ash Content and X-Rays

Ash content was measured in the solid parts and in foamed parts as well.Examples 5-1 and 5-3 were made from Composition 1, where Example 5-1 wassolid and Example 5-3 was foamed. Examples 5-2 and 5-4 were made fromComposition No. 2, where Example 5-3 was solid and Example 5-4 wasfoamed. Measurement was done in three locations plus one location in thesprue, and the results are illustrated in FIG. 9 where flow lengthmeasured in mm is indicated horizontally and ash content in percent isindicated vertically. The first measurement is in the sprue and isindicated as −10 mm. The 0 point is assumed to be the gate of the part.

From the results it can be concluded that the ash content at the end ofthe fill is higher for foamed plaques than solid ones. This can beassociated with transport of longer fibers present in foamed parts atthe end of the flow.

Example 5 Density Distribution

Results for density distribution along a flow path for the MuCell™technology and the method disclosed herein are illustrated in FIG. 10where density measured in g/cm³ is plotted versus flow length measuredin mm. Samples 10-1 and 10-2 were made from the same grade ofpolypropylene having Composition 5 listed in Table 1, while Samples 10-3and 10-4 were made from the sample grade of polypropylene havingComposition 2 listed in Table 1. Samples 10-1 and 10-3 were processedaccording to the method disclosed herein with an injection rate of 45cubic centimeters per second (cm³/s), while Samples 10-2 and 10-4 wereprocessed according to the MuCell™ method with an injection rate of 100cm³/s. As can be seen in FIG. 10, Samples 10-1 and 10-3 demonstrateuniform density distribution with a negligible difference between thebeginning and end of the flow. Conversely, Samples 10-2 and 10-4demonstrate a difference of up to 10%, which is even starker when takinginto consideration that the injection rate for Samples 10-2 and 10-4 wasover double that of Samples 10-1 and 10-3. Density distribution can havean influence on the properties and final performance of any articlesmolded.

Example 6 Flexural Properties

Flexural properties were measured according to Isotropic FlexuralStrength according to ISO 178:2001/Amd 1:2004 and measured in Newtonsper square meter (N/m²). FIGS. 12A to 12D illustrate the results whereisotropic flexural strength was observed to be higher for samplesprocessed according to the method disclosed herein as compared tosamples processed according to the MuCell™ method. Samples 12A1-4 weremade from Composition 1 in Table 1, Samples 12B1-B4 were made fromComposition 2 in Table 1, Samples 12C1-4 were made from Composition 4 inTable 1, and Samples 12D1-4 were made from Composition 5 in Table 1.Each of Samples 12A1-2, 12B1-2, 12C1-2, and 12D1-2 were not foamed,while Samples 12A3-4, 12B3-4, 12C3-4, and 12D3-4 were foamed with a 20%weight reduction. Samples 12A1, 12A3, 12B1, 12B3, 12C1, 12C3, 12D1, and12D3 were made according to the method disclosed herein, while Samples12A2, 12A4, 12B2, 12B4, 12C2, 12C4, 12D2, and 12D4 were made accordingto the MuCell™ method. Samples 12A3, 12A4, 12B3, 12B4, 12C3, 12C4, 12D3,and 12D4 each had a 20% weight reduction as compared to the solidsamples. As can be seen in FIGS. 12A-12D, flexural strength is higherfor the samples produced according to the method disclosed herein. Forexample, flexural properties are higher with the method disclosed hereinfor the foamed samples than for the foamed samples made according to theMuCell™ method.

Example 7 Impact Properties

Impact properties were measured according to ISO 6603-2:2000 (A3).Samples 13A1-13A6 were made from Composition 1 in Table 2, while Samples13B1-13B2 were made from Composition 5 in Table 1. Samples 13A1, 13A2,13B1, and 13B2 were made without foaming; Samples 13A3, 13A4, 13B3, and13B4 were made by foaming with a 20% weight reduction where Samples 13A3and 13B3 were made according to the method disclosed herein and Samples13A4 and 13B4 were made according to the MuCell™ method; Samples 13A5,13A6, 13B5, and 13B6 were made by foaming with a 30% weight reduction,wherein Samples 13A5 and 13B5 were made according to the methoddisclosed herein and Samples 13A6 and 13B6 were made according to theMuCell™ method. Penetration energy at 17 mm displacement measured inJoules per millimeter (J/mm) was measured and is plotted in FIGS. 13Aand 13B. As can be seen in FIGS. 13A and 13B, impact properties arehigher for the samples processed with the method disclosed herein ascompared to the samples processed with the MuCell™ method. Additionally,reduction of the penetration energy for Samples 13A3, 13A4, 13B3, and13B4 is lower for samples 13A3 and 13B4, both processed with the methoddisclosed herein likely due to the longer fibers in each part.

Impact properties for decompression molded samples were also testedaccording to ISO 6603-2:2000 (A3). Results are illustrated in FIGS. 14Aand 14B, where, all of the samples were made with Composition 2. Samples14A1, 14A2, 14B1, and 14B2 were made without foaming, while Samples14A3, 14A4, 14B3, and 14B4 were foamed with a thickness 2.3 times thethickness of the solid part. Samples 14A1, 14A3, 14B1, and 14B3 weremade according to the method disclosed herein, while Samples 14A2, 14A4,14B2, 14B4 were made according to the were made according to the MuCell™method. FIG. 14A illustrates penetration energy at a displacement of 17mm measured in Jimm and FIG. 14B illustrates the maximum force measuredin Newtons (N). As can be seen in FIG. 14B, for the samples processedaccording to the method disclosed herein, in terms of usingdecompression molding, the maximum impact force is increased whenthickness is increased, but for the samples process using the MuCell™method, where despite a thickness increase, the maximum force isreduced. FIG. 14A illustrates that impact energy at 17 mm displacementis reduced due to foaming, but less so with the method disclosed hereinthan with the MuCell™ method.

Embodiment 1: A method of making a foamed part, comprising: introducinga long glass fiber filled polymeric material to a hopper of an injectionmolding machine, wherein the long glass fibers have a pre-moldinglength; melting the long glass fiber filled polymeric material to form amelt; pressurizing a plasticizing unit of the injection molding machinewith a blowing agent, wherein a seal is located between a rotating partand a fixed part of the plasticizing unit; having a seal betweenrotating and fixed part of the plasticizing unit; sealing theplasticizing unit with an airlock mounted between a barrel of theinjection molding machine and the hopper; increasing a pressure of theblowing agent and increasing a back pressure of the injection moldingmachine to homogenize the melt and the blowing agent; and forming thefoamed part; wherein a post-molding length of the long glass fibers inthe foamed part is greater than or equal to a post-molding length oflong glass fibers in a similarly dimensioned foamed part made withoutthe pressurized plasticizing unit.

Embodiment 2: The method of Embodiment 1, wherein the post-moldinglength of the long glass fibers in the foamed part is greater than orequal to a post-molding length of long glass fibers in a similarlydimensioned non-foamed part.

Embodiment 3: The method of Embodiment 1 or Embodiment 2, wherein theblowing agent is a gaseous blowing agent.

Embodiment 4: The method of Embodiment 3, wherein the blowing agent isat least one from carbon dioxide, sodium bicarbonate, azide compounds,ammonium carbonate, ammonium nitrite, monosodium citrate, light metalswhich evolve hydrogen upon reaction with water, chlorinatedhydrocarbons, chlorofluorocarbons, azodicarbonamide,N,N′dinitrosopentamethylenetetramine, trichloromonofluoromethane,trichlorotrifluoroethane, methylene chloride, organic carboxylic acids(such as formic acid, acetic acid, oxalic acid, ricinoleic acid, and soforth), pentane, butane, ethanol, acetone, oxygen gas, nitrogen gas,ammonia gas, and combinations comprising at least one of the foregoing.

Embodiment 5: The method of Embodiment 4, wherein the blowing agent isat least one from nitrogen gas, oxygen gas, carbon dioxide gas, and acombination comprising at least one of the foregoing.

Embodiment 6: The method of any of Embodiments 1-5, wherein a weight ofthe foamed part is reduced by greater than or equal to 5% as compared toa similarly dimensioned non-foamed part including long glass fibers.

Embodiment 7: The method of any of Embodiments 1-6, wherein a foamedinjected plaque has 10% less thickness shrinkage as compared to anon-foamed injected plaque.

Embodiment 8: The method of any of Embodiments 1-7, wherein a foamedinjected plaque has 50% less thickness shrinkage as compared tonon-foamed injected plaque.

Embodiment 9: The method any of Embodiments 1-8, wherein the blowingagent pressure and the back pressure of the injection molding machinediffer by greater than or equal to 0 megaPascals.

Embodiment 10: The method of any of Embodiments 1-9, wherein the blowingagent pressure or the back pressure of the injection molding machine is0 to 10 megaPascals.

Embodiment 11: The method of any of Embodiments 1-10, wherein thedifference between back pressure and the blowing agent pressure of theinjection molding machine is 0 to 5 megaPascals.

Embodiment 12: The method of any of Embodiments 1-11, wherein thepolymeric material is at least one from polycarbonate, polypropylene,polyarylate, polyester, polyphenylene ether, polystyrene, acrylonitrilebutadiene styrene, polyether, polyimide, polyetherimide, polysulfone,polyether ketone, polyether ether ketone, poly(methyl methacrylate),polyvinyl chloride, polysiloxane, and combinations comprising at leastone of the foregoing.

Embodiment 13: The method of any of Embodiments 1-12, wherein aninjection pressure of the injection molding machine is greater than orequal to 10% less in making the foamed part as compared to the injectionpressure when making a non-foamed part including long glass fibers.

Embodiment 14: A polymeric part made by the method of any of Embodiments1-13.

Embodiment 15: A foamed part, comprising: a long glass fiber filledpolymeric material, wherein the long glass fibers have an initial lengthbefore molding of the foamed part and a final length after molding ofthe foamed part; wherein a post-molding length of the long glass fibersin the foamed part is greater than or equal to a post-molding length oflong glass fibers in a similarly dimensioned foamed part made without apressurized plasticizing unit.

Embodiment 16: The foamed part of Embodiment 15, wherein the polymericmaterial is at least one from polycarbonate, polypropylene, polyarylate,polyester, polyphenylene ether, polystyrene, acrylonitrile butadienestyrene, polyether, polyimide, polyetherimide, polysulfone, polyetherketone, polyether ether ketone, poly(methyl methacrylate), polyvinylchloride, polysiloxane, and combinations comprising at least one of theforegoing.

Embodiment 17: The foamed part of Embodiment 15 or Embodiment 16,wherein the final length of the long glass fibers in the foamed part isincreased as compared to a similarly dimensioned non-foamed partincluding long glass fibers.

Embodiment 18: The foamed part of any of Embodiments 15-17, wherein aweight of the foamed part is reduced by greater than or equal to 5% ascompared to a similarly dimensioned non-foamed part including long glassfibers.

Embodiment 19: The foamed part of any of Embodiments 15-18, wherein afoamed injected plaque has 10% less thickness shrinkage as compared to anon-foamed injected plaque.

Embodiment 20: The foamed part of any of Embodiments 15-19, wherein thefoamed part has a number of long glass fibers that is greater than orequal to a number of long glass fibers in a similarly dimensionednon-foamed part including long glass fibers.

Embodiment 21: The foamed part of any of Embodiments 15-20, wherein athickness of the foamed part is increased greater than or equal 50% athickness of a non-foamed part including long glass fibers.

In general, the invention may alternately comprise, consist of, orconsist essentially of, any appropriate components herein disclosed. Theinvention may additionally, or alternatively, be formulated so as to bedevoid, or substantially free, of any components, materials,ingredients, adjuvants or species used in the prior art compositions orthat are otherwise not necessary to the achievement of the functionand/or objectives of the present invention.

All ranges disclosed herein are inclusive of the endpoints, and theendpoints are independently combinable with each other (e.g., ranges of“up to 25 wt. %, or, more specifically, 5 wt. % to 20 wt. %”, isinclusive of the endpoints and all intermediate values of the ranges of“5 wt. % to 25 wt. %,” etc.). “Combination” is inclusive of blends,mixtures, alloys, reaction products, and the like. Furthermore, theterms “first,” “second,” and the like, herein do not denote any order,quantity, or importance, but rather are used to denote one element fromanother. The terms “a” and “an” and “the” herein do not denote alimitation of quantity, and are to be construed to cover both thesingular and the plural, unless otherwise indicated herein or clearlycontradicted by context. The suffix “(s)” as used herein is intended toinclude both the singular and the plural of the term that it modifies,thereby including one or more of that term (e.g., the film(s) includesone or more films). Reference throughout the specification to “oneembodiment”, “another embodiment”, “an embodiment”, and so forth, meansthat a particular element (e.g., feature, structure, and/orcharacteristic) described in connection with the embodiment is includedin at least one embodiment described herein, and may or may not bepresent in other embodiments. In addition, it is to be understood thatthe described elements may be combined in any suitable manner in thevarious embodiments.

Unless otherwise specified herein, any reference to standards,regulations, testing methods and the like, such as ISO 6603 and ISO 178refer to the standard, regulation, guidance or method that is in forceat the time of filing of the present application.

While particular embodiments have been described, alternatives,modifications, variations, improvements, and substantial equivalentsthat are or may be presently unforeseen may arise to applicants orothers skilled in the art. Accordingly, the appended claims as filed andas they may be amended are intended to embrace all such alternatives,modifications variations, improvements, and substantial equivalents.

What is claimed is:
 1. A method of making a foamed part, comprising: introducing a long glass fiber filled polymeric material to a hopper of an injection molding machine, wherein the long glass fibers have a pre-molding length; melting the long glass fiber filled polymeric material to form a melt; pressurizing a plasticizing unit of the injection molding machine with a blowing agent, wherein a seal is located between a rotating part and a fixed part of the plasticizing unit; having a seal between the rotating and fixed parts of the plasticizing unit; sealing the plasticizing unit with an airlock mounted between a barrel of the injection molding machine and the hopper; increasing a pressure of the blowing agent and increasing a back pressure of the injection molding machine to homogenize the melt and the blowing agent; and forming the foamed part; wherein a post-molding length of the long glass fibers in the foamed part is greater than or equal to a post-molding length of long glass fibers in a similarly dimensioned foamed part made without the pressurized plasticizing unit.
 2. The method of claim 1, wherein the post-molding length of the long glass fibers in the foamed part is greater than or equal to a post-molding length of long glass fibers in a similarly dimensioned non-foamed part.
 3. The method of claim 1, wherein the blowing agent is a gaseous blowing agent.
 4. The method of claim 3, wherein the blowing agent is at least one from carbon dioxide, sodium bicarbonate, azide compounds, ammonium carbonate, ammonium nitrite, monosodium citrate, light metals which evolve hydrogen upon reaction with water, chlorinated hydrocarbons, chlorofluorocarbons, azodicarbonamide, N,N′dinitrosopentamethylenetetramine, trichloromonofluoromethane, trichlorotrifluoroethane, methylene chloride, organic carboxylic acids (such as formic acid, acetic acid, oxalic acid, ricinoleic acid, and so forth), pentane, butane, ethanol, acetone, oxygen gas, nitrogen gas, ammonia gas, and combinations comprising at least one of the foregoing.
 5. The method of claim 4, wherein the blowing agent is at least one from nitrogen gas, oxygen gas, carbon dioxide gas, and a combination comprising at least one of the foregoing.
 6. The method of claim 1, wherein a weight of the foamed part is reduced by greater than or equal to 5% as compared to a similarly dimensioned non-foamed part including long glass fibers.
 7. The method of claim 1, wherein a foamed injected plaque has 10% less thickness shrinkage as compared to non-foamed injected plaque.
 8. The method of claim 1, wherein the blowing agent pressure and the back pressure of the injection molding machine differ by greater than or equal to 0 megaPascals.
 9. The method of claim 1, wherein the blowing agent pressure or the back pressure of the injection molding machine is 0 to 10 MegaPascals.
 10. The method of claim 1, wherein the difference between back pressure and the blowing agent pressure of the injection molding machine is 0 to 5 MegaPascals.
 11. The method of claim 1, wherein the polymeric material is at least one from polycarbonate, polypropylene, polyarylate, polyester, polyphenylene ether, polystyrene, acrylonitrile butadiene styrene, polyether, polyimide, polyetherimide, polysulfone, polyether ketone, polyether ether ketone, poly(methyl methacrylate), polyvinyl chloride, polysiloxane, and combinations comprising at least one of the foregoing.
 12. The method of claim 1, wherein an injection pressure of the injection molding machine is greater than or equal to 10% less in making the foamed part as compared to the injection pressure when making a non-foamed part including long glass fibers.
 13. A polymeric part made by the method of claim
 1. 14. A foamed part, comprising: a long glass fiber filled polymeric material, wherein the long glass fibers have an initial length before molding of the foamed part and a final length after molding of the foamed part; wherein a post-molding length of the long glass fibers in the foamed part is greater than or equal to a post-molding length of long glass fibers in a similarly dimensioned foamed part made without a pressurized plasticizing unit.
 15. The foamed part of claim 14, wherein the polymeric material is at least one from polycarbonate, polypropylene, polyarylate, polyester, polyphenylene ether, polystyrene, acrylonitrile butadiene styrene, polyether, polyimide, polyetherimide, polysulfone, polyether ketone, polyether ether ketone, poly(methyl methacrylate), polyvinyl chloride, polysiloxane, and combinations comprising at least one of the foregoing.
 16. The foamed part of claim 14, wherein the final length of the long glass fibers in the foamed part is increased as compared to a similarly dimensioned non-foamed part including long glass fibers.
 17. The foamed part of claim 14, wherein a weight of the foamed part is reduced by greater than or equal to 5% as compared to a similarly dimensioned non-foamed part including long glass fibers.
 18. The foamed part of claim 14, wherein a foamed injected plaque has 10% less thickness shrinkage as compared to a non-foamed injected plaque.
 19. The foamed part of claim 14, wherein the foamed part has a number of long glass fibers that is greater than or equal to a number of long glass fibers in a similarly dimensioned non-foamed part including long glass fibers.
 20. The foamed part of claim 14, wherein a thickness of the foamed part is increased greater than or equal 50% a thickness of a non-foamed part including long glass fibers. 